In the following code, is the attribute (variable/member) a class attribute
or an instance attribute?  I thought that it was an instance attribute and
that the class attribute was created in __init__().

My biggest question is why self.v has a value of "Consequences" in the
_init__() of f2?  Is self.v not an instance variable?

pwatson [ /home/pwatson/src/python/c ] 270
$ cat d.py
#! /usr/bin/env python

class whatisit:
  v = "Ambiguous"

  def __init__(self):
    print '=== __init__', self.v, whatisit.v
    self.v = "Truth"
    whatisit.v = "Consequences"

  def showem(self):
    print '=== showem  ', self.v, whatisit.v

class C(object):
      x=1 # class attribute
      def __init__(self):
          self.x=self.x # the class attribute becomes an instance attribute

c=C()

C.x=2

print c.x,C.x

This code prints 1,2. You see that the line self.x=self.x is far
from being trivial: Python looks first for the self on the right,
looking for the instance attribute self.x: since it does not find anything,
it looks for the class attribute; then the class attribute
is assigned to the instance attribute on the left hand side.

If you forget the apparently useless self.x=self.x line, you get a
different result:

class C(object):
      x=1 # class attribute
      def __init__(self):
          pass

c=C()

C.x=2

print c.x,C.x

This prints 2,2, since the class attribute has been changed to 2
and c has no instance attribute.

Hoping-having-not-increased-your-confusion-ly,

Thanks for everyone's help, including Mike.

class Foo (object) :
    foo = 'spam'
    def __init__ (self) :
        print Foo.foo, self.foo
        self.foo = 'ham'
        print Foo.foo, self.foo